JP6118555B2 - Soil inherent thermal resistance measuring device, soil inherent thermal resistance measuring method, and soil inherent thermal resistance measuring system - Google Patents

Description

  The present invention relates to a soil specific heat resistance measurement device, a soil specific heat resistance measurement method, and a soil specific heat resistance measurement system suitable for measuring soil specific heat resistance.

  Generally, the transmission capacity that enables power transmission through a power cable is greatly affected by the soil thermal resistance around the soil in which the power cable is embedded. For this reason, when designing a power cable, as one of the basic data for calculating the allowable current, it is necessary to measure the soil specific thermal resistance and grasp the thermal condition in the buried route of the power cable.

さらに、土壌に差し込んだ探針体の３箇所の各計測温度により求めた土壌固有熱抵抗値を演算手段で平均化し、この平均値を土壌固有熱抵抗値として表示手段に表示するという技術が開示されている。 Patent Document 1 discloses a “soil thermal resistance measuring device”. In particular, using the measured temperature θ ₂ 2 minutes after the heater is energized and the soil is heated, and the calculated temperature θ ₂₀ 20 minutes after the start of heating, the soil specific thermal resistance value g is Ask.

Further, a technique is disclosed in which the soil specific heat resistance value obtained from each measured temperature of the three probe bodies inserted into the soil is averaged by the calculation means, and this average value is displayed on the display means as the soil specific heat resistance value. Has been.

Patent Document 2 discloses “a method of inserting a probe bar at the time of measuring soil thermal resistance and a guide bar used therefor”. In particular, as a technique for measuring the soil specific heat resistance, a probe bar equipped with a heat source and a temperature measuring means is inserted into the soil, and the temperature change when heated with a heat source for a certain time is measured by the temperature measuring means. A technique for obtaining a thermal resistance by calculation from a temperature gradient is disclosed.
Here, the temperature gradient is an inclination of a straight line obtained continuously until the measurement target region becomes linear. As a calculation method, the soil specific thermal resistance is calculated from the temperature at the arbitrary time after the start of energization at two points and the temperature at the arbitrary time, the depth of the heating element, and the power consumption of the heat source. The temperature change when the probe bar is heated with a heat source for a certain period of time is measured, and the thermal resistance is obtained from this temperature gradient.

In Patent Document 3, the relationship between log (t) indicating elapsed time and temperature is plotted on a semi-logarithmic graph, and judgment is made based on the gradient of the temperature gradient. A technique of calculating the gradient between log (t) and temperature by performing approximation using the method of least squares in a region where sufficient time has passed and it has been determined that the relationship between log (t) and temperature is linear. Is disclosed.
Here, the least square method is a method used for organizing measurement data, and is the best fit from n data (x1, y1), (x2, y2), ... (xn, yn). The straight line to be obtained is set to y = ax + b, and a and b are obtained from the equation of the least square method.

Japanese Patent Laid-Open No. 11-23503 JP 2008-164478 A JP 2001-281071 A

When measuring the soil specific heat resistance, there are multiple work processes because the soil heating by the heat source, the temperature change recording in the soil, and the soil specific heat resistance must be calculated for each measurement. The burden of each work by the person increased and became complicated.
In particular, in the previous stage of calculating the soil specific thermal resistance, there is a work of recording after measuring in units of 1 minute for a measurement time of about 60 minutes as a record of temperature change. Work such as creation, determination of a regression line within a linear region, and calculation of soil specific thermal resistance is complicated. In addition, depending on the operator's analysis experience, the judgment of the measurement target region may differ, resulting in variations in the calculated soil specific thermal resistance value, which causes a decrease in calculation accuracy. there were.

In addition, there is a method of setting an arbitrary time (t1, t2) in advance in order to make it easy to calculate the soil specific thermal resistance, but the temperature change varies depending on the soil layer configuration to be measured, Since the soil layer configuration of the measurement site is unknown, there is a problem that the calculation accuracy of the soil specific thermal resistance value may be lowered.
Therefore, it is simplified without reducing accuracy for the work required to create a semilogarithmic graph, to determine a regression line within a linear area, and to calculate the soil specific heat resistance, etc., which is performed when analyzing the soil specific heat resistance. It is anxious to become. In addition, a soil specific heat resistance measurement device, a soil specific heat resistance measurement method, and a soil specific heat resistance measurement system capable of obtaining soil specific heat resistance values with extremely low differences regardless of the years of analysis experience of the worker are eagerly desired. Has been.
The present invention has been made in view of the above, and as its purpose, the processing from obtaining soil measurement data to calculating the soil specific heat resistance is simplified, and a highly accurate soil specific heat resistance value is obtained. It is to provide a soil specific heat resistance measuring device, a soil specific heat resistance measuring method, and a soil specific heat resistance measuring system.

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a long heating element inserted into the soil, and at least one of detecting the temperature of the soil arranged at a predetermined portion in the longitudinal direction of the heating element. A soil specific thermal resistance measuring device for obtaining a thermal resistance of the soil from a thermocouple and the temperature of the soil detected by the thermocouple, wherein the soil temperature detected by the thermocouple and the heating element are energized. Data acquisition means for acquiring measurement data comprising an elapsed time since the start, and of the measurement data acquired by the data acquisition means, the first elapsed time from the start of energization A regression line creation means for creating a regression line approximated to the measurement data up to a second elapsed time after an elapsed time of 1, the regression line between the first elapsed time and the second elapsed time Measurement data and A correlation coefficient calculating means for calculating a correlation coefficient with the regression line, and when the correlation coefficient calculated by the correlation coefficient calculation means is equal to or greater than a predetermined reference value, Based on the temperature value calculating means for calculating the temperature value at the first and second elapsed time, the first and second elapsed time, and the temperature value at the first and second elapsed time, When the correlation coefficient calculated by the specific thermal resistance calculation means for calculating the specific thermal resistance of the soil and the correlation coefficient calculation means is less than a predetermined reference value, the first and second elapsed times are calculated. Resetting means for arbitrarily resetting is provided, and the regression line creation means creates a regression line approximated to the measurement data from the first elapsed time to the second elapsed time reset by the resetting means. characterized in that it.

According to the present invention, the measurement data consisting of the temperature of the soil detected by the thermocouple and the elapsed time since the start of energization of the heating element is acquired, and the energization is started among the acquired measurement data. A regression line approximated to the measurement data from the first elapsed time to the second elapsed time after the first elapsed time is created, and the first elapsed time and the second elapsed time When the correlation coefficient between the measured data and the regression line is calculated and the calculated correlation coefficient is equal to or greater than a predetermined reference value, the first and second elapsed times from the slope of the regression line are calculated. Calculates the temperature value, and acquires soil measurement data by calculating the specific thermal resistance of the soil based on the first and second elapsed times and the temperature values at the first and second elapsed times. The process from the start to the calculation of the specific thermal resistance of the soil is simplified and the soil is highly accurate Yes thermal resistance can be obtained.
As a result, it has been simplified without reducing the accuracy of the work required for analysis of soil specific heat resistance, such as the creation of a semi-logarithmic graph, determination of a regression line within a linear area, and calculation of soil specific heat resistance. Regardless of the years of analysis experience of the operator, it is possible to obtain soil specific heat resistance values with extremely low differences.

It is a figure which shows sectional drawing of the electric power cable embed | buried under soil, and its heat | fever equivalent circuit. It is a figure which shows measuring a temperature rise when a probe bar is embedded in the ground and a fixed electric power is supplied to a heat generation source. It is a figure which shows the relationship between the temperature characteristic in soil, and elapsed time with a graph. It is a block diagram which shows the structure of the soil specific heat resistance measuring apparatus which concerns on 1st Embodiment of this invention. It is a flowchart for demonstrating the calculation process of the soil specific heat resistance by the soil specific heat resistance measuring apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the example of a display of the message box containing a message. It is a figure which shows an example of the temperature change measurement recording data which is measurement data. It is a figure which shows an example of the sheet paper on which the logarithmic graph was printed. It is a figure which shows an example of the sheet paper on which the logarithmic graph and the regression line were printed. It is a figure which shows an example of the logarithmic graph currently displayed on the display screen of a display part. It is a figure which shows that the regression line is displayed with the logarithmic graph on the display screen of a display part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
Hereinafter, the principle of measuring the specific thermal resistance of soil will be described with reference to the drawings.
<Power cable transmission capacity (cable design-allowable current calculation)>
The allowable current of a power cable is a current that can flow without deteriorating the life of the insulator even when the power is continuously or repeatedly energized, even if the temperature rises due to the generated loss. Escape to. Here, the generated loss is generated from a conductor (conductor loss), a metal sheath / shield (sheath loss), etc. by passing a current through the power cable, and is generated from an insulator (dielectric loss) by applying a voltage. To do.
As shown in FIG. 1, when laying the pipeline 1 including the power cable 1b in the soil, the anticorrosion layer 1a is filled between the inner wall of the pipeline 1 and the power cable 1b. Here, the power cable 1b includes a conductor 1d disposed at the center of the cross section, an insulator 1c covering the conductor 1d, and a metal sheath layer 1e covering the insulator 1c.
As shown in FIG. 1, the thermal equivalent circuit of the power cable includes a soil thermal resistance R5, a cable surface dissipation thermal resistance R3, an anticorrosion layer thermal resistance R2, and an insulator thermal resistance R1 between the soil temperature T2 and the conductor temperature T1. It becomes a thermal resistance circuit that is connected sequentially.

<Outline of soil specific thermal resistance measurement>
With reference to the explanatory diagram shown in FIG. 2, each device for measuring the temperature rise characteristic of the soil will be described.
When determining the transmission capacity of the power cable, it is necessary to calculate the temperature rise of the power cable caused by the current. For that purpose, it is necessary to measure the specific thermal resistance value of the soil that is the temperature medium, that is, the surrounding soil where the power cable is embedded, and to accurately grasp the thermal condition.
There are two methods for measuring the specific thermal resistance value: “soil sampling method” and “in-situ probe method”. In general, the measurement by the “in-situ probe method” is simple and economical, so it is widely used.

As shown in FIG. 2, this method includes a heater 3 a that is a long heating element inside, and a metal having thermocouples 3 b to 3 d that are arranged at predetermined positions in the longitudinal direction of the heater 3 a and detect the temperature of the soil. A probe rod 3 made of a pipe made of steel is inserted into the ground. Next, constant power is supplied from the generator and power supply unit 2 to the heater 3a serving as a heat source. Next, temperature data detected by the thermocouples 3 b to 3 d provided on the probe bar 3 inserted at a depth of 800 mm, 1200 mm, and 1600 mm from the ground surface is acquired by the measuring device 4.
In this method, the operator visually checks the three points of temperature data acquired by the measuring device 4, plots them on a semi-log graph paper, and calculates the thermal resistance based on the three points of temperature rise characteristics.

と求められる。
図３に示すように、グラフ上において、時間軸に対して片対数を採用する。図３では、ヒータ３ａに通電を開始して上昇領域になり、次に、測定対象領域がある勾配を有する直線状になり、飽和領域に入るまで測定を継続し、得られた測定対象領域の直線の傾きが熱抵抗となる。 FIG. 3 is a graph showing the relationship between temperature characteristics and elapsed time in soil.
At this time, the soil specific thermal resistance g [° C./cm/W] is the heater length L [cm], the power consumption W [W], and any time within the range where the temperature-time curve after heating the heater becomes a straight line. From the surface temperature θ1, θ2 [° C.] of the probe bar at t1, t2 [min], t1, t2,

Is required.
As shown in FIG. 3, a semi-logarithm is adopted with respect to the time axis on the graph. In FIG. 3, energization of the heater 3 a is started to become an ascending region, and then the measurement target region becomes a straight line having a certain gradient, and the measurement is continued until the saturation region is entered. The slope of the straight line becomes the thermal resistance.

<Temperature change at each measurement location>
A regression line is determined from the temperature characteristics at the measured location.
When the measurement location is different, the measurement target region is different for each measurement value. Therefore, in the method of setting an arbitrary time at the time of measurement in advance, there is a possibility that the calculation accuracy of the obtained soil specific thermal resistance value is lowered.
Therefore, in the first embodiment of the present invention, as shown in FIG. 2, the on-site measurement method is a measurement by the “probe method in situ”, and the recording of temperature data in the soil is a recording medium. Recorded in the data logger 5 (recording device). Then, in a local or indoor environment, by taking temperature data from the data logger 5 into the personal computer PC, a semilogarithmic graph is automatically created by data processing by application software installed in the personal computer PC.

With reference to the block diagram shown in FIG. 4, the structure of the soil intrinsic thermal resistance measuring apparatus which concerns on 1st Embodiment of this invention is demonstrated. Note that the configuration shown in FIG. 4 includes a data logger 5 (recording device) and a soil specific thermal resistance measurement device 20 (calculation device) that obtains the thermal resistance of the soil from the measurement data input from the data logger 5. It can be applied to the soil specific thermal resistance measurement system.
The soil specific thermal resistance measurement apparatus 20 includes an I / F unit 21, a keyboard 22, a mouse 23, an I / O unit 24, a hard disk 25, a RAM unit 26, a display unit 27, a display control unit 28, and the like. The control unit 29 and the printer unit 30 are provided. The I / F unit 21 is connected to one end of a communication cable connected to the data logger 5 and performs data communication according to a predetermined communication protocol. The I / O unit 24 is connected to the keyboard 22 and outputs a character code input by an operator's operation to the control unit 29. The I / O unit 24 is connected to the mouse 23 and outputs operation information input by an operation by the operator to the control unit 29.

The hard disk 25 stores past measurement data, an operating system OS, and application software. The RAM unit 26 temporarily stores measurement data received from the data logger 5 and control data as a work area of the control unit 29. Further, the RAM unit 26 reads out a program about the operating system OS and application software from the hard disk 25 by the control unit 29 and develops the program on the RAM unit 26.
The display control unit 28 has a VRAM for developing image data, and outputs the image data read from the VRAM to the display unit 27. The display unit 27 displays the image data input from the display control unit 28 on the display screen.
The control unit 29 reads out a program for the operating system OS and application software from the hard disk 25, develops it on the RAM unit 26, and sequentially executes the program to control the operation of each unit provided in the apparatus. . The printer unit 30 prints image data such as a logarithmic graph and a regression line on sheet paper in response to an instruction from the control unit 29.

<Soil intrinsic heat resistance calculation process>
With reference to the flowchart shown in FIG. 5, the calculation process of the soil specific heat resistance by the soil specific heat resistance measuring apparatus which concerns on 1st Embodiment of this invention is demonstrated.
First, in step S <b> 10, the control unit 29 captures measurement data from the data logger 5 through the I / F unit 21 into the RAM unit 26 and stores the measurement data in the hard disk 25. FIG. 7 is a diagram illustrating an example of temperature change measurement record data which is measurement data. The measurement data includes a soil temperature θ detected by the thermocouples 3b to 3d shown in FIG. 2 and an energization time t which is an elapsed time since the energization of the heater 3a is started.

Then, in step S15, the control unit 29 extracts the measured temperature θ energization time t from the measurement data stored in the RAM unit 26, the horizontal axis by calculating the natural logarithm Log e _t relative energizing time t The measured temperature θ is plotted on the vertical axis, and a logarithmic graph is developed on the RAM unit 26 and created. By transferring the image data relating to the logarithmic graph created on the RAM unit 26 to the VRAM provided in the display control unit 28, the logarithmic graph is displayed on the display screen of the display unit 27 as shown in FIG. The
At this time, the graph print button 41 is displayed on the display screen of the display unit 27. The control unit 29 determines whether or not the graph print button 41 is clicked according to the operation of the mouse 23. When the graph print button 41 is clicked according to the operation of the mouse 23, the control unit 29 outputs logarithmic graph display data developed on the RAM unit 26 to the printer unit 30. As a result, the sheet paper (see FIG. 8) on which the logarithmic graph is printed is discharged from the printer unit 30.

Next, in step S20, the control unit 29 sets t1 = 10 minutes and t2 = 40 minutes as temporary fixed times for the logarithmic graph developed on the RAM unit 26, and the temperature in the time range t1-t2. Create a regression line that approximates the data. As shown in FIG. 11, a regression line is displayed on the display screen of the display unit 27 together with a logarithmic graph.
At this time, the graph print button 41 is displayed on the display screen of the display unit 27. The control unit 29 determines whether or not the graph print button 41 is clicked according to the operation of the mouse 23. When the graph print button 41 is clicked according to the operation of the mouse 23, the control unit 29 outputs the display data of the logarithmic graph and the regression line developed on the RAM unit 26 to the printer unit 30. . As a result, the sheet paper (see FIG. 9) on which the logarithmic graph and the regression line are printed is discharged from the printer unit 30.

Here, for simplicity of explanation, the points (Log e _t, θ) on the logarithmic graph each point of the XY coordinate system (X, Y) and replaced will be described.
First, two coordinates (Xs, Ys) and (Xe, Ye) on the XY coordinate axes are defined. In the process of obtaining the regression line, attention is paid to one point whose position is defined by the XY coordinate axes, and this is expressed in the form of coordinates (Xi, Yi).
If the coordinates of the attention point (Xi, Yi), that is, the locus of (X1, Y1), (X2, Y2), ..., (Xi, Yi), ... (Xn, Yn), ... are approximated by a straight line, The angle between this straight line and the horizontal line (X axis) corresponds to the slope of the straight line.

Linear approximation of the locus of coordinates (Xi, Yi) can be obtained by performing regression analysis. A method of obtaining a regression line of Y with respect to X is simply as follows.
The formula for the regression line of Y with respect to X is
Y = AX + B (2)
Where A is the regression coefficient of Y with respect to X (linear gradient).
A = {NΣXiYi− (ΣXi) (ΣYi)} / {NΣXi ² − (ΣXi) ² } (3)
Find A, then
B = ΣYi / N−AΣXi / N (4)
To obtain B.

Next, in step S23, the control unit 29 calculates a correlation coefficient ρ between each point (Xi, Yi) of the time range t1-t2 in the measurement target region and the regression line represented by the equation (2).
The correlation coefficient is obtained by adding the following processing in addition to the processing procedure (formulas (2) to (4)).
In other words, if the X and Y positions are reversed, another regression line is created. The equation for the regression line of X with respect to Y is
X = CY + D (5)
And in this case,
C = {NΣXiYi− (ΣXi) (ΣYi)} / {NΣYi ² − (ΣYi) ² } (6)
Find C, then
D = ΣXi / N−CΣYi / N (7)
To obtain D. Assuming that the correlation coefficient ρ of X and Y is given by equations (3) and (6),
ρ = ± √ | AC | (8)
It becomes. In addition, the selection of the code | symbol in Formula (8) is made into the code | symbol of the numerator of A or C. The closer the absolute value of the correlation coefficient ρ is to 1, the better the linear approximation of coordinates.
In steps S15, S20, and S23 described above, a logarithmic graph, a regression line, and a correlation coefficient ρ are created and calculated. However, in addition to such a method, a well-known example such as Excel (registered trademark) is used. It may be calculated using the spreadsheet application software.

Next, in step S25, the control unit 29 determines whether or not the calculated correlation coefficient ρ of the regression line is, for example, 0.8 (reference value) or more. When the correlation coefficient ρ of the regression line is 0.8 or more, the process proceeds to step S30. On the other hand, if the correlation coefficient ρ of the regression line is less than 0.8, the process proceeds to step S40.
When the correlation coefficient ρ of the regression line is 0.8 or more, in step S30, the control unit 29 calculates the temperatures θ1 and θ2 at t1 and t2 from the linear gradient (A).

In step S35, the control unit 29 calculates the soil specific thermal resistance g by substituting the times t1 and t2 and the temperatures θ1 and θ2 into the equation (1). The control unit 29 outputs a text code indicating the calculated soil specific thermal resistance g to the display control unit 28. The display control unit 28 converts the text code into display data and displays it on the display unit 27. As a result, the soil specific thermal resistance g is displayed on the display screen of the display unit 27 as shown in FIG.
In addition, in the flowchart shown in FIG. 5, in order to simplify description, for example, the soil specific thermal resistance g was calculated based on the measurement data of the depth of soil surface 0.8 m, but separately, 1.2 m, The soil specific thermal resistance g may be calculated based on the measurement data having a depth of 1.6 m.

<Movement of time range t1, t2>
On the other hand, when the correlation coefficient ρ of the regression line is less than 0.8, the time range due to the soil soil, that is, the time range when the regression line is obtained in step S20 t1 = 10 minutes, t2 = 40. The minute setting may be inappropriate.
Therefore, in step S40, the control unit 29 draws a text image on the VRAM provided in the display control unit 28, and for example, a text image of a message “Please move the time range t1, t2.” Is displayed on the display screen of the display unit 27. Here, since the positions of the time ranges t1 and t2 displayed on the display screen of the display unit 27 are moved according to the cursor operation with the mouse 23 by the operator, the time ranges t1 and t2 after the movement are newly set. To adopt.
Next, in step S45, the control unit 29 creates a regression line that approximates the temperature data of the newly adopted time range t1-t2 for the logarithmic graph developed on the RAM unit 26. As a result, a new regression line is displayed on the display screen of the display unit 27 together with the logarithmic graph.

  In this way, when the calculated correlation coefficient ρ is less than the reference value 0.8, the first and second elapsed times t1 and t2 can be arbitrarily reset, and the reset first A regression line approximated to the measurement data from the elapsed time t1 of 1 to the second elapsed time t2 is created. Thereby, the data of the area | region with much dispersion | variation contained in measurement data can be excluded, and the dispersion | variation in the soil intrinsic | native thermal resistance value calculated in a back | latter stage can be reduced.

In step S50, the control unit 29 draws a text image on the VRAM provided in the display control unit 28, and includes, for example, a text image of a message “Measurement error?” On the display screen shown in FIG. A message box 31 (see FIG. 6A) is displayed. The control unit 29 determines whether the “none” button 31 a or the “present” button 31 b included in the message box 31 is clicked according to the operation of the mouse 23. If the “none” button 31a is operated, the process proceeds to step S55. On the other hand, if the “Yes” button 31b is operated, the process proceeds to step S65.
When the “none” button is operated, in step S55, the control unit 29 calculates the temperatures θ1 and θ2 at times t1 and t2 from the linear gradient (A). Next, in step S60, the control unit 29 calculates the soil specific thermal resistance g by substituting the times t1 and t2 and the temperatures θ1 and θ2 into the equation (1). The control unit 29 outputs a text code indicating the calculated soil specific thermal resistance g to the display control unit 28. The display control unit 28 converts the text code into display data and displays it on the display unit 27. As a result, the soil specific thermal resistance g is displayed on the display screen of the display unit 27 as shown in FIG.

<Measurement error measures>
When there is measurement data at a position extremely deviated from the logarithmic graph or regression line displayed on the display screen of the display unit 27, a singular point is displayed. When the “Yes” button 31b is operated by the operator, it is assumed that error data is mixed in part of the measurement data.
Therefore, in step S65, the control unit 29 draws a text image on the VRAM provided in the display control unit 28. For example, a message box 33 including a text image of a message “Please delete error temperature data” is displayed on the display screen shown in FIG.

Here, it is assumed that the operator visually confirms the temperature data displayed on the display screen of the display unit 27 and finds that some numerical values are incorrect. In accordance with the operation of the mouse 23 by the operator, the cursor displayed on the display screen of the display unit 27 is moved to the numerical value of the temperature data (FIG. 10, right side, file input screen). Next, when a double click operation of the mouse 23 is detected, the control unit 29 deletes the numerical value from the RAM unit 26.
Since the error data is deleted in step S65, in step S70, the control unit 29 extracts the energization time t and the measurement temperature θ from the measurement data stored in the RAM unit 26. Then, the control unit 29, the horizontal axis by calculating the natural logarithm Log e _t relative energizing time t, to create and expand the logarithmic graph on RAM section 26 by plotting the measured temperature θ on the vertical axis. By transferring the image data relating to the logarithmic graph created on the RAM unit 26 to the VRAM provided in the display control unit 28, the logarithmic graph is displayed on the display screen of the display unit 27 as shown in FIG. The Next, the control unit 29 creates a regression line that approximates the temperature data of the newly adopted time range t1-t2 for the logarithmic graph created on the RAM unit 26. As a result, a new regression line is displayed on the display screen of the display unit 27 together with the logarithmic graph.

  In this way, a logarithmic graph made up of temperature and elapsed time is drawn from the acquired measurement data, and arbitrary measurement data can be deleted from the acquired measurement data. Next, a regression line that approximates the measurement data from the first elapsed time t1 to the second elapsed time t2 after any measurement data is deleted is created. Thereby, the data of the area | region with much dispersion | variation contained in measurement data can be deleted, and the dispersion | variation in the soil intrinsic | native thermal resistance value calculated in a latter step can be decreased.

Next, in step S75, the control unit 29 calculates the temperatures θ1 and θ2 at t1 and t2 from the linear gradient (A). Next, in step S80, the control unit 29 calculates the soil specific thermal resistance g by substituting the times t1 and t2 and the temperatures θ1 and θ2 into the equation (1). The control unit 29 outputs a text code indicating the calculated soil specific thermal resistance g to the display control unit 28. The display control unit 28 converts the text code into display data and displays it on the display unit 27. As a result, the soil specific thermal resistance g is displayed on the display screen of the display unit 27 as shown in FIG.
In the use test, for example, three persons, such as a skilled person and an inexperienced person with experience of 3 years or more, confirmed the analysis accuracy of the soil specific heat resistance g using the soil specific heat resistance measuring device 20, and as a result, experienced and inexperienced The difference from the above was within ± 3 ° C. · cm / W. Regardless of the number of analysis experiences of the worker, the following factors have contributed to the improvement in the accuracy of the soil specific thermal resistance analysis. In other words, by automating the creation of a semilogarithmic graph, determination of a regression line within a linear area, determination of the correlation coefficient between the measurement data and the regression line, calculation of soil specific thermal resistance, etc. This is because it can be greatly shortened. In addition, by adding processing such as resetting of time ranges t1 and t2 and deletion of erroneous temperature data, variations in soil specific thermal resistance values can be reduced.

Thus, the measurement data which consist of the temperature of the soil detected by the thermocouples 3b-3d and the elapsed time after starting electricity supply to the heater 3a are acquired. Of the obtained measurement data, a regression line approximated to the measurement data from the first elapsed time t1 after the start of energization to the second elapsed time t2 after the first elapsed time t1. Create. Furthermore, when the correlation coefficient ρ between the measurement data and the regression line between the first elapsed time t1 and the second elapsed time t2 is calculated, and the calculated correlation coefficient ρ is equal to or greater than a predetermined reference value The temperature values θ1 and θ2 at the first and second elapsed times t1 and t2 are calculated from the gradient A of the regression line. Then, the specific thermal resistance g of the soil is calculated based on the first and second elapsed times and the temperature values θ1 and θ2 at the first and second elapsed times t1 and t2. Thereby, the process from obtaining the soil measurement data to calculating the soil specific heat resistance g can be simplified, and a highly accurate soil specific heat resistance value can be obtained.
As a result, it has been simplified without reducing the accuracy of the work required for analysis of soil specific heat resistance, such as the creation of a semi-logarithmic graph, determination of a regression line within a linear area, and calculation of soil specific heat resistance. Can be Furthermore, soil specific heat resistance values with extremely low differences can be obtained regardless of the years of analysis experience of the operator.

Second Embodiment
In the first embodiment, in step S20 shown in FIG. 5, the control unit 29 sets t1 = 10 minutes and t2 = 40 minutes as temporary fixed times for the logarithmic graph developed on the RAM unit 26. Is set in advance. And it was comprised so that the regression line approximated to the temperature data of time range t1-t2 might be created.
On the other hand, in the second embodiment, the date and time data when the analysis work is performed is added to the time ranges t1 and t2 when the soil specific thermal resistance values are calculated in steps S35, S60, and S80 shown in FIG. And stored in the hard disk 25. Then, at the time of the next analysis work, in step S20, the control unit 29 reads the time ranges t1 and t2 to which the latest date and time data is added from the hard disk 25 with respect to the logarithmic graph developed on the RAM unit 26. And it is comprised so that the regression line approximated to the temperature data of this time range t1-t2 may be created.

Normally, each measurement point in field work is set at intervals of several tens of meters to several hundreds of meters with respect to the planned embedding place of the power cable. For this reason, there may be few changes in the stratum and geology at each measurement point, and it can be assumed that measurement data at a plurality of measurement points are collected in a lump.
In such a case, the time ranges t1 and t2 to which the latest date and time data are added are read from the hard disk 25, and a regression line approximating the temperature data in the time range t1 to t2 is created. Next, in step S23, the control unit 29 calculates a correlation coefficient ρ between each point (Xi, Yi) in the time range t1-t2 in the measurement target region and the regression line represented by the equation (2).
When the measurement points are close, since there is little change in the stratum and geology at each measurement point, the correlation coefficient ρ is often 0.8 or more, so that the processing time required for the analysis work can be shortened.

<Third Embodiment>
In the first embodiment, in step S40, the control unit 29 draws a text image on the VRAM provided in the display control unit 28, for example, “move time ranges t1, t2. A message box including a text image of the message “.” Is displayed on the display screen of the display unit 27. Here, since the positions of the time ranges t1 and t2 displayed on the display screen of the display unit 27 are moved according to the operation of the mouse 23 by the operator, the time ranges t1 and t2 after the movement are newly adopted. Is configured to do.
On the other hand, in the third embodiment, for example, when an arbitrary time range is fixed to 40 minutes, near the temperature point (for example, 5 minutes) on the semilogarithmic graph displayed on the display screen. Then, it is assumed that the operator operates the mouse 23 and clicks with the cursor close. Here, the time corresponding to the click point on the display screen is assumed to be t1. Next, in step S45, a regression line is drawn from the measurement data in which the time ranges t1 and t2 are between 5 minutes and 45 minutes, and the temperatures θ1 and θ2 at the time of t1 (10 minutes) · t2 (40 minutes) are calculated from the gradient. May be configured to calculate the soil specific thermal resistance by reverse calculation.

In areas where power cables are planned to be buried, there are areas where there are significant changes in the strata and geology at each measurement point in actual field work. It can be assumed that measurement data of a plurality of different measurement points are sequentially collected and stored in the data logger 5.
In such a case, the time ranges t1 and t2 are changed for each analysis operation, and a regression line approximated to the temperature data in the time range t1-t2 is created. Next, in step S45, the control unit 29 calculates a correlation coefficient ρ between each point (Xi, Yi) in the time range t1-t2 in the measurement target region and the regression line represented by the equation (2).
The processing shown in the third embodiment is executed even when the measurement point is different from the measurement point at the time of the previous analysis work and the area and the geological change are remarkable for each point. Thereby, an arbitrary time range can be easily changed by a single click operation, and the time required for the analysis work can be shortened.

<Fourth embodiment>
In the first embodiment, after finishing the processing in steps S40 and S45, the control unit 29 draws a text image on the VRAM provided in the display control unit 28 in step S50. For example, a message box 31 including a text image of a message “Is measurement error?” Is displayed on the display screen shown in FIG. 11, and the “none” button 31 a or the “present” button 31 b included in the message box 31 is displayed on the mouse. It was configured to determine whether or not the button was clicked in response to the operation 23.
On the other hand, in 4th Embodiment, after finishing the process by step S40, S45, the control part 29 is a correlation coefficient with each point in elapsed time t1-t2, and a regression line (it produces by S45). ρ is calculated in advance. Then, it is determined whether or not the calculated correlation coefficient ρ is 0.8 or more. If the correlation coefficient ρ of the regression line is 0.8 or more, it is considered that there is no measurement error, and the process proceeds to step S55. It may be configured.

Thereby, arbitrarily set time ranges t1 and t2 are newly adopted in step S40, and in step S45, a newly adopted time range t1− is applied to the logarithmic graph developed on the RAM unit 26. A regression line approximated to the temperature data of t2 is created. Next, the correlation coefficient ρ between each point in the elapsed time t1-t2 and the regression line is calculated, and if the correlation coefficient ρ of the regression line is 0.8 or more, it is considered that there is no measurement error. Next, in step S55, the control unit 29 calculates temperatures θ1 and θ2 at t1 and t2 from the linear gradient (A). Next, in step S60, the control unit 29 calculates the soil specific thermal resistance g by substituting the times t1 and t2 and the temperatures θ1 and θ2 into the equation (1). The control unit 29 outputs a text code indicating the calculated soil specific thermal resistance g to the display control unit 28. The display control unit 28 converts the text code into display data and displays it on the display unit 27. As a result, the soil specific thermal resistance g is displayed on the display screen of the display unit 27 as shown in FIG.
Thereby, it is possible to speed up the processing from newly adopting arbitrarily set time ranges t1 and t2 to calculating the soil specific thermal resistance g. By executing the processing shown in the fourth embodiment, the time required for the analysis work can be shortened.

<Fifth Embodiment>
In the first embodiment, after the error data is deleted from the RAM unit 26 in step S65, a regression line is created in step S70 by approximating the newly adopted temperature data in the time range t1-t2. Keep it. Next, in step S75, the temperatures θ1 and θ2 at t1 and t2 were calculated from the linear gradient (A).
On the other hand, in the fifth embodiment, after deleting the error data from the RAM unit 26 in step S65, in step S70, a regression line approximated to the temperature data in the newly adopted time range t1-t2 is created. Keep it. Next, a correlation coefficient between each point in the newly adopted elapsed time t1-t2 and the regression line (created in S70) is calculated, and whether the calculated correlation coefficient ρ is 0.8 or more is determined. When the correlation coefficient ρ of the regression line is 0.8 or more, it is determined that there is no measurement error, and the process proceeds to step S75. On the other hand, when the correlation coefficient ρ of the regression line is less than 0.8, it may be considered that there is a measurement error and the process proceeds to step S65.

Thus, after deleting the error data from the RAM unit 26, a regression line approximated to the temperature data in the newly adopted time range t1-t2 is created. Next, the correlation coefficient ρ between each point in the newly adopted elapsed time t1-t2 and the regression line is calculated, and when the correlation coefficient ρ of the regression line is 0.8 or more, the linear gradient Temperatures θ1 and θ2 at t1 and t2 are calculated from (A). Next, the soil intrinsic thermal resistance g is calculated by substituting the times t1 and t2 and the temperatures θ1 and θ2 into the equation (1).
As described above, it is possible to speed up the process from the deletion of the error data from the RAM unit 26 until the calculation of the soil specific thermal resistance g with high accuracy. By executing the processing shown in the fifth embodiment, the time required for the analysis work can be shortened.

  DESCRIPTION OF SYMBOLS 1 ... Pipe line, 1a ... Anticorrosion layer, 1b ... Power cable, 1c ... Insulator, 1d ... Conductor, 1e ... Metal sheath layer, 2 ... Power supply unit, 3 ... Probe bar, 3a ... Heater, 3b ... Thermocouple, 3c ... thermocouple, 3d ... thermocouple, 4 ... measuring instrument, 5 ... data logger, 20 ... soil specific thermal resistance measuring device, 21 ... I / F unit, 22 ... keyboard, 23 ... mouse, 24 ... I / O unit , 25 ... hard disk, 26 ... RAM section, 26 ... RAM section, 27 ... display section, 28 ... display control section, 29 ... control section, 30 ... printer section, 31 ... message box, 31a ... button, 31b ... button, 33 ... Message box, 41 ... Graph print button

Claims (4)

A long heating element inserted into the soil, at least one thermocouple arranged at a predetermined position in the longitudinal direction of the heating element to detect the temperature of the soil, and the soil temperature from the soil temperature detected by the thermocouple A soil specific thermal resistance measuring device for determining the thermal resistance of
Data acquisition means for acquiring measurement data consisting of the temperature of the soil detected by the thermocouple, and the elapsed time from the start of energization of the heating element,
Of the measurement data acquired by the data acquisition means, approximate to the measurement data from the first elapsed time since the start of energization to the second elapsed time after the first elapsed time A regression line creation means for creating a regression line,
Correlation coefficient calculating means for calculating a correlation coefficient between the measurement data and the regression line between the first elapsed time and the second elapsed time;
Temperature value calculating means for calculating temperature values at the first and second elapsed times from the slope of the regression line when the correlation coefficient calculated by the correlation coefficient calculating means is equal to or greater than a predetermined reference value. When,
Specific heat resistance calculating means for calculating the specific heat resistance of the soil based on the first and second elapsed times and the temperature value at the first and second elapsed times;
Re-setting means for arbitrarily resetting the first and second elapsed times when the correlation coefficient calculated by the correlation coefficient calculating means is less than a predetermined reference value;
The regression line creation means creates a regression line that approximates the measurement data from the first elapsed time to the second elapsed time reset by the resetting means, apparatus. Graph drawing means for drawing a logarithmic graph of temperature and elapsed time from the measurement data acquired by the data acquisition means;
A data deletion unit that deletes any of the measurement data with respect to the measurement data acquired by the data acquisition unit,
The regression line creation means creates a regression line that approximates measurement data from a first elapsed time to a second elapsed time after any measurement data is deleted by the data deletion means. The soil specific heat resistance measuring device according to claim 1. A long heating element to be inserted into the soil, at least one thermocouple which is arranged at a predetermined position in the longitudinal direction of the heating element to detect the temperature of the soil, and the heat of the soil from the temperature detected by the thermocouple A soil specific thermal resistance measurement method for determining resistance,
A data acquisition step of acquiring measurement data consisting of the temperature of the soil detected by the thermocouple, and the elapsed time from the start of energization of the heating element,
Of the measurement data acquired by the data acquisition step, approximate to the measurement data from the first elapsed time since the start of energization to the second elapsed time after the first elapsed time. A regression line creation step for creating a regression line,
A correlation coefficient calculating step of calculating a correlation coefficient between the measurement data and the regression line between the first elapsed time and the second elapsed time;
A temperature value calculating step of calculating a temperature value at the first and second elapsed times from the slope of the regression line when the correlation coefficient calculated by the correlation coefficient calculating step is equal to or greater than a predetermined reference value; When,
A specific heat resistance calculating step of calculating a specific heat resistance of the soil based on the first and second elapsed times and the temperature value at the first and second elapsed times;
A reset step for arbitrarily resetting the first and second elapsed times when the correlation coefficient calculated by the correlation coefficient calculation step is less than a predetermined reference value;
The regression line creation step creates a regression line approximated to the measurement data from the first elapsed time to the second elapsed time reset by the resetting step, Method. A long heating element to be inserted into the soil, at least one thermocouple arranged at a predetermined position in the longitudinal direction of the heating element to detect the temperature of the soil, and the temperature detected by the thermocouple are recorded as measurement data A soil specific thermal resistance measurement system comprising: a recording device that performs the calculation; and a calculation device that obtains the thermal resistance of the soil from the measurement data input from the recording device,
The recording device comprises:
Data recording means for recording measurement data consisting of the temperature of the soil detected by the thermocouple and the elapsed time from the start of energization of the heating element,
The arithmetic unit is:
Of the measurement data input from the recording device, the measurement data approximated to the measurement data from the first elapsed time after the start of energization to the second elapsed time after the first elapsed time. A regression line creation means for creating a regression line;
Correlation coefficient calculating means for calculating a correlation coefficient between the measurement data and the regression line between the first elapsed time and the second elapsed time;
Temperature value calculating means for calculating temperature values at the first and second elapsed times from the slope of the regression line when the correlation coefficient calculated by the correlation coefficient calculating means is equal to or greater than a predetermined reference value. When,
Specific heat resistance calculating means for calculating the specific heat resistance of the soil based on the first and second elapsed times and the temperature value at the first and second elapsed times;
Re-setting means for arbitrarily resetting the first and second elapsed times when the correlation coefficient calculated by the correlation coefficient calculating means is less than a predetermined reference value;
The regression line creation means creates a regression line that approximates the measurement data from the first elapsed time to the second elapsed time reset by the resetting means, system.

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